Annoying Miss Popularity, Miriam, is having a pool party that the girls don’t want to miss. But it’s a risky activity for three mermaids: their secret could be out. Spurned by Lewis, Rikki discovers her mermaid power is to boil water at will! For a hot-head like Rikki, this is dangerous. Meanwhile, Cleo’s close friend Lewis is getting closer to finding out about the girls; almost busting Emma and Rikki, as mermaids. At the pool party, Cleo’s plan not to go swimming goes out the window as Zane and his mates toss her into the pool. But luckily the guys walk away before she turns into a mermaid. The only thing is – she needs someone who’s not a mermaid to get her out – Lewis.